Conventional thin film transistor liquid crystal display (“TFT-LCD”) devices or low temperature poly-silicon (“LPTS”) LCD devices include a matrix of transistors for actuating display of an image. Each transistor includes a gate electrically coupled to a scan line, a source electrically coupled to a data line, and a drain electrically coupled to a storage capacitor. Scan lines and data lines are in turn respectively coupled to a scan line driving circuit and a data line driving circuit disposed at an LCD interface. The data line driving circuit usually includes shift registers and switches to control application of data into an LCD device through a plurality of data signal lines. Specifically, data, for example, video image data, are provided from the shift registers through the data signal lines and the switches to the data lines of an LCD device.
FIG. 1 is a layout of a conventional LCD interface showing how a conventional technique provides data signals to an LCD device. Referring to FIG. 1, a first set of data including data signals DS1 to DS12 is provided to an LCD device (not shown) from a shift register (not shown) to a plurality of data signal lines DL1 to DL12, and data lines DK1 . . . DKn of the LCD device through switches SW1 . . . SWn. For instance, a first data signal DS1 of the first set of data DS1 to DS12 is provided by a first shift register to data signal line DL1 and then through a switch SW1 to a data line DK1 which corresponds to, for example, a red (“R”) sub-pixel region of a pixel (not shown) of an LCD device. Subsequently, a second data signal DS2 of the first set of data DS1 to DS12 is provided by the first shift register to data signal line DL2 and then through a switch SW2 to a data line DK2, which corresponds to a green (“G”) sub-pixel region of a pixel. Likewise, a third data signal DS3 of the first set of data DS1 to DS12 is provided by the first shift register to data signal line DL3 and then through a switch SW3 to a data line DK3, which corresponds to a blue (“B”) sub-pixel region of a pixel. The R, G and B sub-pixel regions constitute a pixel of the LCD device.
As a result, the first set of data is provided in the order of writing data signals DS1 to DS12 from the first data signal line DL1 to the final data signal line DL12. After the first set of data, a second set of data DS13 to DS24 is provided by a second shift register (not shown) to the LCD panel in a same order of writing from data signal line DL1 to data signal line DL12. This order of applying data signals from a shift register to data lines of the LCD device is also applicable to any set of data that follows.
The conventional technique may encounter a disadvantage in that a difference in the gray scale between the same sub-pixel regions of two adjacent pixels may become visible to the human eyes. The problem is caused by a difference in resistance and distributed capacitance present between two data lines of significantly different transmission lengths. For example, for the R sub-pixel regions of two adjacent pixels, the transmission length associated with data signal DS10 of the first set of data is significantly longer than that of data signal DS13 of the second set of data. Similarly, for the G sub-pixel regions, the transmission length associated with data signal DS11 is significantly longer than that of data signal DS14. Again, for the B sub-pixel regions, the transmission length associated with data signal DS12 is significantly longer than that of data signal DS15. As a result, the pixel represented by data signals DS10 to DS12 of the first set of data may have a visible difference in the gray scale from an adjacent pixel represented by data signals DS13 to DS15 of the second set of data.
The problem of different gray scale usually occurs at two adjacent pixels where in the respective R, G and B sub-pixel regions are coupled to a leading set of data signal lines such as DL1 to DL3 and an ending set of data signal lines such as DL10 to DL12, respectively. Besides, the problem would become worse as more data signal lines are used.